Large Diameter Hose

[Diane E]

There's a debate going on in my dept. about large diameter hose and "safety".

What's the highest pressure you've used 5 inch hose under? And did it break?

Depending on the brand of LDH you are using, check the manufacturers web-site. Angus LDH is designed to operate up to 225 PSI, it is pressure tested to 450 PSI, and its burst pressure is 675 PSI.

[ 11-14-2001: Message edited by: MANNY3591 ]

[BLACKSHEEP1]

Here's some food for thought, usually departments use ldh hose for moving lot's of water at low friction loss. Even though the burst strength might be fairly high, normally 150psi will not be exceeded. The reason being is that most (all?) pumps rated capacity is at 150psi. So if you go above 150 you lose gpms, so if capacity is your thing, it wouldn't pay to exceed 150psi. (this example is at draft). Something else to consider is that 5in hose can move about 1,000gpm. so if you like to "lay the 5in and charge the deck gun" you're limiting yourself to just under 1,000 gal,(depending on hydrant pressure and friction loss) so, even though ldh sounds good, you still cannot get capacity through this hose in a forward lay. One other thing that comes to mind, when you order your hose, make sure that the wrench will collapse the locks as you remove the coupling. There are several brands of couplings out there and although they will lock together, one person unlocking/uncoupling the hose can be a real cluster if all of the wrenches/locks/couplings are different.As far as safety is concerned I've used this stuff for 24years w/o any major problems, occaisionally a hose would get twisted and spin off the coupling, but the locks prevent this now.....call,gotta-go

[bfpd36]

I've only seen one instance where a 5" line, in good condition,(no holes etc) burst.
It's a long story, but the investigation deduced that it was a combination of a pressure surge and a water hammer. It caused the 5" to pull away from the coupling, sending the compression ring flying through the air and landing approx 150 feet from the truck.
P.S.
No one was injured.

[RKSmith]

We have been using 5 inch LDH for 18 years and to my knowledge have never had one burst.
We have added external relief valves to the
steamer connections on both sides of all our apparatus. They dump a 125 psi. The locking devices on the storz connectors are a pain, but they do make operations safer.

[RKSmith]

We have been using 5 inch LDH for 18 years and to my knowledge have never had one burst.
We have added external relief valves to the
steamer connections on both sides of all our apparatus. They dump a 125 psi. The locking devices on the storz connectors are a pain, but they do make operations safer.

[BLACKSHEEP1]

Sorry about that.. let's see, never get capacity, make sure the locks/wrenches are compatible, stay away from snap tight with the plastic inserts, they pull off, but the aluminum ones are ok. Really this stuff is the only way to go especially if you have cotton now. Years ago no one here wanted it either until the engines with the plastic were back in bed and the guys with the cjrl were still hanging it. Good luck on your crusade.

[Dalmatian90]

Most LDH is "supply LDH" which is supposed to be used at 200psi or less. "Attack LDH" has a higher pressure, 250psi I think off the top of my head.

So if you go above 150 you lose gpms, so if capacity is your thing, it wouldn't pay to exceed 150psi. (this example is at draft)
This partially depends on the length of lays you're looking at. 1500' and less (with a good, very low FL LDH) 1500gpm holds true. We routinely lay 2500', sometimes more, in our rural area. We can deliver 1000gpm over 2500', more or less, with a 200psi pump pressure. If we limited ourselves to 150psi, we'd lose some flow with out the extra psi's to push the 1000gpm that far.

Now here is a point to ponder for us rural folks...

It is possible to setup a scenario with 5" hose, especially lower-FL ones like Angus Hi-Vol, where you're pumping at 200psi from draft. And the hose goes down a hill quickly (steeply?) enough that Elevation Gain overcomes Friction Loss to create a point on the hose you have more than 200psi!

[BLACKSHEEP1]

Dalmation, we're on the same page. ldh is great stuff but it takes a little getting used to, and of course everyone has a little different response area. We can supply 1450gallons, 1,000 ft away on a 50 psi hydrant,the plug engine uses a short 35ft 5in to hook up to the hydrant,if you use a 6in soft supply you can do even better. One more thing to remember make darn sure you buy coupling and appliances w/true 5in holes in them, there is alot of junk out there w/3in hole that pretend to be 5in. Jaffrey,Jaffey..I forget the exact name, sell an excellent gate type true 5in inlet/outlets. They are currently out of business but I think they were bought out by TFT (good move for TFT). There are others out there however.

[mongofire_99]

With todays LDH, the installation, care and feeding of the coupling is the weak point in system. All of the "modern" LDH failures I've heard about are coupling failures, failure to lock it, failure to ensure the collar bolts are tight, that kind of thing...

Burst? I've seen a motor drive sequence (pics in a fire service magazine, think it was an old FF News - anyone?) of a guy standing on 200psi charged 5" with a pickhead axe, strike and puncture the 5" and all it did was spray out of the hole, it didn't burst or tear more and the line could have stayed in service if it had happened on scene.

But here's some food for thought (and maybe useless trivia...)

If you are making forward lays from a 50psi hydrant less than 500', a single 5" will bring almost 1,600gpm to the pump, dual 5"ers will bring 3,100gpm.

At 100' of the same hydrant, one 5" brings 3100gpm 500', duals bring 7000gpm

From a 25 psi hydrant 100' away a single 5" will bring 2,500gpm and duals will bring close to 5,000gpm

Forward lays from a 50 psi hydrant and needing 1,000gpm from it:

5" will take it 1200'
4" will take it 400'
3" less than 100' and it takes two 3" lines to to get it 200'
2.5" less than 100' and two of them still won't get it 100'

Forward lays from a 25psi hydrant and needing 1,000gpm

5" will take it 600'
4" will take it 200'
3" less than 100' and it takes two 3" lines to to get it 100'
2.5" less than 100' and two of them still won't get it 100'

5" 1,000gpm Relay:

@150psi - 3000'
@200psi - 4000'
@250psi - 1 mile

[ 11-15-2001: Message edited by: mongofire_99 ]

[Pyro128]

Large diameter hoses are used for supply only, 1 bar on the entrance of the pump is enough, the rest is a loss of power. What they taught us was "high pressure, low capacity - low pressure - high capacity".
I wouldn't be too afraid of hoses breaking under pressure.
I did see them burst once. That was on a training, and was caused by bad coupling (hose flew off the iron ring).